Thread Content
Vacuum filters mainly use the principle of vacuum filtration to achieve solid-liquid separation. According to the structure, they can be divided into vacuum drum, vacuum disc, ceramic, vacuum suction filtration and other forms. Different from the principle of filter press filtration, vacuum filtration is mainly used in situations where filtration is easier, such as when the particle size is relatively large, the material is not sticky, and filter cakes are easy to form. At the same time, due to the small pressure difference formed by vacuum filtration, the theoretical absolute pressure difference is only 1 bar, so the solid content of the filter cake is not high. Compared with other filtration methods, the main advantage of vacuum horizontal belt filters lies in filter cake washing, especially when washing water consumption is high. Countercurrent washing is used, that is, washing in the opposite direction from the cake discharge end to the feed end. The principle is that from the cake unloading end to the feed end, the impurity concentration changes from low to high, so the impurity concentration of the corresponding washing effluent from the cake unloading end is also lower than that of the feeding end, so the washing effluent from the cake unloading end can be reused to the corresponding front end for washing. At present, the vacuum horizontal belt filter can achieve 13 levels of countercurrent washing, and the washing water consumption is only 10 to 15% of conventional washing. For special applications, when the mother liquor is required to be recycled, usually the concentration of the washing water at the feed end can be the same as that of the mother liquor to ensure recycling. In the filtration of materials containing organic solvents, the vacuum horizontal belt filter also shows obvious performance. Sometimes, the sealed vacuum horizontal belt filter can be used for the filtration of various volatile organic solvent materials. Under nitrogen sealing conditions, the continuous operation of the system can be achieved without the risk of leakage. Typical applications include: CMC, cellulose, aramid, Vc, Vb, CTA/PTA, wet fractionation, etc.